\begin{table}[htbp]\centering
\def\sym#1{\ifmmode^{#1}\else\(^{#1}\)\fi}
\caption{Utilization index -- Subcomponents}
\begin{tabular}{l*{4}{c}}
\toprule
                    &\multicolumn{1}{c}{(1)}&\multicolumn{1}{c}{(2)}&\multicolumn{1}{c}{(3)}&\multicolumn{1}{c}{(4)}\\
                    &\multicolumn{1}{c}{\textbf{\begin{tabular}[c]{@{}c@{}}Utilization\\index\end{tabular}}}&\multicolumn{1}{c}{\begin{tabular}[c]{@{}c@{}}Vaccination rates,\\children\textless 36 months\end{tabular}}&\multicolumn{1}{c}{\begin{tabular}[c]{@{}c@{}}\% of visits to HC,\\vs. other providers\end{tabular}}&\multicolumn{1}{c}{\begin{tabular}[c]{@{}c@{}}Number of visits\\ to HC\end{tabular}}\\
\midrule
Full treatment      &       0.027   &       0.054   &       0.034   &      -0.001   \\
                    &     (0.022)   &     (0.035)   &     (0.032)   &     (0.027)   \\
Constant            &      -0.020   &      -0.011   &      -0.001   &      -0.017   \\
                    &     (0.016)   &     (0.025)   &     (0.023)   &     (0.020)   \\
\midrule
N                   &       7,288   &       4,212   &       7,288   &       7,288   \\
R$^{2}$             &       0.230   &       0.057   &       0.178   &       0.284   \\
Adjusted p-value (FT)&       0.298   &       0.370   &       0.446   &       0.981   \\
\bottomrule
\end{tabular}
\end{table}
